perf tools: Rename build libperf to perf

Rename build libperf to perf, because it's used to build perf.

The libperf build object name will be used for libperf library.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190213123246.4015-4-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/trace/beauty/Build

@@ -1,15 +1,15 @@
-libperf-y += clone.o
-libperf-y += fcntl.o
-libperf-y += flock.o
+perf-y += clone.o
+perf-y += fcntl.o
+perf-y += flock.o
 ifeq ($(SRCARCH),$(filter $(SRCARCH),x86))
-libperf-y += ioctl.o
+perf-y += ioctl.o
 endif
-libperf-y += kcmp.o
-libperf-y += mount_flags.o
-libperf-y += pkey_alloc.o
-libperf-y += arch_prctl.o
-libperf-y += prctl.o
-libperf-y += renameat.o
-libperf-y += sockaddr.o
-libperf-y += socket.o
-libperf-y += statx.o
+perf-y += kcmp.o
+perf-y += mount_flags.o
+perf-y += pkey_alloc.o
+perf-y += arch_prctl.o
+perf-y += prctl.o
+perf-y += renameat.o
+perf-y += sockaddr.o
+perf-y += socket.o
+perf-y += statx.o